For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit: By which also he went and preached unto the spirits in prison; Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water. The like figure whereunto even baptism doth also now save us (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ: (1 Peter 3:18-21 KJV)
I have always wondered about this passage that talks about Jesus preaching to the disobedient spirits in prison. Some like to say this proves there is a second chance...a purgatory of sorts. After some research, it made more sense.
You have to take the verse within the whole context of the section talking about the days of Noah. Christ preached by the Holy Spirit through Noah to the spirits of disobedient people of that time. They did not repent and they are now "in prison" (Hell). This passage is not saying Christ went to prison and preached to them but rather stating that He preached to them who are now in prison. During the time Noah took to build the ark, God was longsuffering with them, waiting, giving them a chance to repent, preaching to them by the Spirit through Noah.
We know from the Bible message as a whole that once a person dies without Christ, there are no second chances. So it makes no sense that Christ would go to "prison" and preach to those who have rejected Him. For what purpose?
The other error that is often made with this passage is baptismal regeneration...the idea that baptism saves us. People who put that spin on this are ignoring the fact that it says, "The like figure whereunto even baptism doth also now save us (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ:"
Baptism is a figure symbolizing our salvation just like the ark symbolizes salvation. We must not read more in to Scripture than what is already there.
The main and most important point of the whole passage is that Christ suffered ONCE for our sins to bring us to God, and that baptism is the answer of a good conscience toward God. Everything we do should be done with a good conscience toward God.